Swaging Operation For Relieving Stress From A Bushing Flange

ABSTRACT

A swaging process is utilized for reducing the diameter of an outer ring of a bushing using a swaging tool including a gap or profile in the area of a flange of the outer ring in order to prevent or reduce the stresses that are formed in the flange radii area.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/159,834, filed on Mar. 13, 2009. The entire disclosure of the aboveapplication is incorporated herein by reference.

FIELD

The present disclosure relates to bushings for supporting an end portionof a suspension arm on a vehicle body, the suspension arm can be forsuspending a wheel of a motor vehicle.

BACKGROUND AND SUMMARY

This section provides background information related to the presentdisclosure which is not necessarily prior art.

With reference to FIG. 1, bushings 10 are commonly used for supportingan end portion of a suspension arm 12 on a vehicle body. As shown inFIG. 2, known bushings 10 include an outer ring 14 and an inner supportmember 16 as well as a rubber element 18 disposed between the outer ring14 and the inner support member 16. The outer ring 14 can be providedwith a radially outwardly extending flange 14 a at a proximal endthereof. In the known bushings 10, the rubber element 18 is vulcanizedinto a gap between the outer ring 14 and the support member 16. Thismethod tends to cause the rubber element 18 to shrink during the coolingof the bushing 10 that follows vulcanization, resulting in internaltension in the rubber element 18 which can be disadvantageous. In orderto reduce the internal tension on the rubber element 18, it has beenknown to swage the outer ring 14 to reduce its diameter therebyrelieving the internal tension of the rubber element 18.

As illustrated in FIG. 3, the swaging process is typically performed bya segmented swaging tool 20. The segmented swaging tool 20 can include aplurality of semi-cylindrical segments 22 that, when compressed radiallyinward together combine to generally form a cylindrical wall having aninner diameter smaller than an outer diameter of the pre-swaged outerring. According to a known example swaging process, it has been known toreduce the outer diameter of the ring by 3 mm, from 69 mm to 66 mm, inorder to relieve internal tension from the rubber element 18.

Upon insertion of the bushing 10 into the suspension arm, it has beenknown to flare the distal end 14 b of the outer ring 14 in an outwarddirection by a forming process in order to retain the bushing in anaperture in the suspension arm. The forming process used to flare thedistal end 14 b of the outer ring 14 applies significantly higher forceson the flange 14 a of the outer ring 14 than the forces typicallyapplied in inserting the outer ring 14 into the end of the suspensionarm 12. By way of non-limiting example, a force required for pressfitting the bushing 10 into the end of the suspension arm 12 can beapproximately 16 kN while the force required for flaring the distal end14 b of the outer ring 14 can be approximately 60 kN. It has been foundthat the larger force applied for flaring the distal end of the outerring can cause cracking in the radii area of the flange 14 a of theouter ring 14.

It is a discovery of the present disclosure that the swaging processutilized for reducing the diameter of the outer ring 14 creates internalstresses located at the radii area at the intersection of the flangeportion 14 a with the cylindrical body of the outer ring 14.Accordingly, to prevent these stresses, the swaging tool, according tothe present disclosure, is provided with a gap or profile in the area ofthe flange in order to prevent or reduce the stresses that are formed inthe flange radii area.

This section provides a general summary of the disclosure, and is not acomprehensive disclosure of its full scope or all of its features.

Further areas of applicability will become apparent from the descriptionprovided herein. The description and specific examples in this summaryare intended for purposes of illustration only and are not intended tolimit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only ofselected embodiments and not all possible implementations, and are notintended to limit the scope of the present disclosure.

FIG. 1 is a plan view of a portion of a conventional suspension controlarm having a bushing inserted therein;

FIG. 2 is a cross-sectional view of a conventional bushing;

FIG. 3 is a schematic illustration of a conventional swaging processapplied to a bushing;

FIG. 4 is a schematic illustration of a swaging process applied to abushing according to the principles of the present disclosure;

FIG. 5 is a cross-sectional view of a bushing formed according to theswaging process illustrated in FIG. 4;

FIG. 6 is a schematic illustration of an alternative swaging processapplied to a bushing according to the principles of the presentdisclosure; and

FIG. 7 is a cross-sectional view of a bushing formed according to theswaging process illustrated in FIG. 6.

Corresponding reference numerals indicate corresponding parts throughoutthe several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference tothe accompanying drawings.

Example embodiments are provided so that this disclosure will bethorough, and will fully convey the scope to those who are skilled inthe art. Numerous specific details are set forth such as examples ofspecific components, devices, and methods, to provide a thoroughunderstanding of embodiments of the present disclosure. It will beapparent to those skilled in the art that specific details need not beemployed, that example embodiments may be embodied in many differentforms and that neither should be construed to limit the scope of thedisclosure. In some example embodiments, well-known processes,well-known device structures, and well-known technologies are notdescribed in detail.

Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,”“lower,” “above,” “upper,” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. Spatiallyrelative terms may be intended to encompass different orientations ofthe device in use or operation in addition to the orientation depictedin the figures. For example, if the device in the figures is turnedover, elements described as “below” or “beneath” other elements orfeatures would then be oriented “above” the other elements or features.Thus, the example term “below” can encompass both an orientation ofabove and below. The device may be otherwise oriented (rotated 90degrees or at other orientations) and the spatially relative descriptorsused herein interpreted accordingly.

With reference to FIG. 4, a swaging tool 120 includes a plurality ofsemi-cylindrical segments 122. The number of semi-cylindrical segments122 can be greater than two, and more preferably, about 12. Thesemi-cylindrical segments 122 each include a semi-cylindrical wallportion 124 that is designed to engage the outer ring 14 over a majorityof the axial length of the outer ring 14. The semi-cylindrical segments122 also include a profile portion 126 at an end edge thereof that isdesigned to be adjacent to the flange 14 a of the outer ring 14 duringthe swaging process. The profile portion 126 can gradually extend awayfrom the semi-cylindrical wall section 124 or can be stepped in order toprovide a relief area 128 between the radius region 130 of the flange 14a and the profile portion 126. The relief area 128 provided by theprofile portion 126 allows for the swaging process of FIG. 4 to form anouter ring 14′ shown in FIG. 5, having an increased thickness region 132in the radii area 130 that has reduced internal stress.

With reference to FIG. 6, the swaging tool 220 includes a plurality ofsemi-cylindrical segments 222. The semi-cylindrical segments 222 eachinclude a semi-cylindrical wall portion 224. The semi-cylindrical wallportion 224 of each segment 222 is spaced from the flange 14 a of theouter ring 14 by a gap distance G.

The swaging process illustrated in FIG. 6 results in an outer ring 14″that includes a free forming profile 140 spaced from the flange 14 aabout a distance equal to the gap G. This swaging process results in aradii area 130 that has reduced internal stress. It is noted that thedistance of the gap G can be determined based upon a specificapplication, however, it has been noted during testing that gaps of ⅛inch and ¼ inch have been found to be sufficient in order to remove thestress risers from the radii region 130 such that the outer ring 14 canbe subjected to the forces required to flare the distal end 14 b of theouter ring 14 without causing damage to the radii region of the flange14 a.

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the invention. Individual elements or features ofa particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the invention, and all such modificationsare intended to be included within the scope of the invention.

1. A swaging operation for an outer ring of a bushing having a rubberelement disposed between the outer ring and an inner support member,comprising: inserting said bushing in a segmented swaging tool, saidsegmented swaging tool including a plurality of semi-cylindricalsegments that, when compressed radially inward together combine togenerally form a cylindrical wall having an inner diameter smaller thanan outer diameter of the pre-swaged outer ring, said semi-cylindricalsegments each including a profile portion at an edge thereof in an areaof a flange of the outer ring, said profile portion extending radiallyoutward from a semi cylindrical wall section of said semi-cylindricalsegments.
 2. The swaging operation according to claim 1, wherein saidprofile portion gradually extends away from said semi cylindrical wallsection of said semi-cylindrical segments.
 3. The swaging operationaccording to claim 1, wherein said profile portion is stepped away fromsaid semi cylindrical wall section of said semi-cylindrical segments. 4.A swaging operation for an outer ring of a bushing having a rubberelement disposed between the outer ring and an inner support member,comprising: inserting said bushing in a segmented swaging tool, saidsegmented swaging tool including a plurality of semi-cylindricalsegments that, when compressed radially inward together combine togenerally form a cylindrical wall having an inner diameter smaller thanan outer diameter of the pre-swaged outer ring, said semi-cylindricalsegments each including an edge portion nearest a flange of the outerring being spaced from said flange of the outer ring by a gap.